Moulds for fabricating large wind rotor blades of composite materials are well known in the art. For example, U.S. Pat. No. 7,223,091 describes one such mould assembly. Rotor blade mould assemblies are generally composed of two mould portions, a top portion and a bottom portion that are closed about a longitudinal hinge line using a turn-over mechanism or crane. Usually, the bottom portion of the mould assembly is maintained in a fixed position while the top portion is rotated over the bottom portion so that the openings of the two mould portions oppose each other. Glue or other bonding paste is applied to the inner face of the bottom blade portion before the top blade portion descends thereon.
High accuracy and automation of the opening and closing of the mould is very desirable. Accurate positioning of the mould portions in relation to each other during closure of the mould is necessary in order to obtain precise engagement of mould portion edges and a high degree of bonding between the mould portions during the blade curing cycle.